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Updated: May 15, 2026
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A Swine Model of Neonatal Asphyxia
Published on: October 11, 2011
Interrupted oxygen pre-breathing and decompression outcomes in swine
Seth Y Flagg1, David P Regis, Kyle Petersen
1Fort Belvoir Community Hospital, Family Medicine Residency, Fort Belvoir, VA, USA.
Aviation, Space, and Environmental Medicine
|January 12, 2013
Summary
Oxygen prebreathe (OPB) before rapid decompression reduces severe decompression sickness (DCS). However, longer air interruptions significantly diminish OPB
Area of Science:
- Hyperbaric medicine and physiology
- Decompression sickness research
- Submarine escape and rescue operations
Background:
- Submarine rescue operations pose significant risks of severe decompression sickness (DCS).
- Oxygen prebreathe (OPB) is a known countermeasure to reduce DCS risk.
- The duration of OPB's protective effect against DCS, especially after air interruptions, is not well understood.
Purpose of the Study:
- To investigate the hypothesis that the protective benefits of OPB against DCS are lost after air interruptions.
- To determine the impact of varying air interruption durations on DCS incidence following OPB.
- To evaluate the effectiveness of extended OPB in mitigating DCS after air exposure.
Main Methods:
- A swine saturation model (70-kg) was used to simulate conditions relevant to submarine escape.
- Swine underwent rapid decompression after 22 hours at 2.7 ATA, following pre-treatments of 45 or 60 minutes of OPB with varying air interruption periods (30, 45, 60 minutes).
- Control groups included swine with no OPB (negative control) and 45 minutes of OPB without air interruption (positive control).
Main Results:
- The group with 120 minutes of OPB followed by a 60-minute air interruption (OPB120/60) showed a statistically significant reduction in Type II DCS incidence (11%) compared to the negative control (80%).
- Log rank tests indicated that longer OPB durations (OPB120/60) significantly reversed the negative effects of air interruption on DCS-free survival compared to shorter OPB durations (OPB45).
- OPB45/60 demonstrated a statistically significant difference in DCS-free survival compared to the positive control (OPB45).
Conclusions:
- The protective efficacy of oxygen prebreathe against severe decompression sickness is diminished by increasing durations of air interruption.
- Extended oxygen prebreathe periods may help to reverse the detrimental effects of air interruptions on DCS-free survival.
- Findings suggest that protocols for submarine escape should consider the timing and duration of oxygen prebreathe relative to potential air exposures.
